This converter turns atmospheres into bar instantly, using the exact factor 1 atmosphere = 1.01325 bar. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
Standard atmospheric pressure by definition — 101,325 pascals exactly. Almost exactly atmospheric pressure; standard in European industry and diving.
Because the relationship is a simple proportion, one multiplication does the whole job. The table further down gives pre-computed values for the amounts people look up most often, and the result panel also reports the reverse conversion so you can check the figure both ways.
The formula
atmospheres- The amount you are converting, measured in atmospheres
1.01325- The exact number of bar in one atmosphere
bar- The converted result
How it works, step by step
- Enter the number of atmospheres you want to convert.
- The value is multiplied by 1.01325, the exact conversion factor.
- The result is displayed in bar, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 atmospheres
Multiply 5 by 1.01325. That gives 5.0663 bar. A quick sanity check: one atmosphere is larger than one bar, so the number should get bigger — and it does.
Converting 72 atmospheres
72 × 1.01325 = 72.954 bar. Working backwards, 72.954 ÷ 1.01325 returns 72 atmospheres, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many bar are in one atmosphere?
Exactly 1.01325. Every conversion on this page is that single number multiplied by your input, so the result carries no rounding error beyond what is shown.
What is the formula to convert atmospheres to bar?
Bar = atmospheres × 1.01325. To reverse it, divide instead: atmospheres = bar ÷ 1.01325, which is the same as multiplying by 0.9869232667.
Is the atmosphere bigger than the bar?
Yes. One atmosphere equals 1.01325 bar, so it is the larger unit.
Why does my answer differ slightly from other atmospheres to bar converters?
Most differences come from rounding the factor too early. This tool keeps full double precision through the calculation and only rounds at the final display step, and it also shows the unrounded value so you can see exactly where any difference appears.
What is a atmosphere?
Standard atmospheric pressure by definition — 101,325 pascals exactly.
What is a bar?
Almost exactly atmospheric pressure; standard in European industry and diving.
Atmospheres to bar reference table
| Atmospheres | Bar |
|---|---|
| 0.5 atm | 0.506625 bar |
| 1 atm | 1.0132 bar |
| 2 atm | 2.0265 bar |
| 3 atm | 3.0397 bar |
| 5 atm | 5.0663 bar |
| 10 atm | 10.1325 bar |
| 15 atm | 15.1988 bar |
| 20 atm | 20.265 bar |
| 25 atm | 25.3313 bar |
| 50 atm | 50.6625 bar |
| 75 atm | 75.9938 bar |
| 100 atm | 101.325 bar |
| 250 atm | 253.3125 bar |
| 500 atm | 506.625 bar |
| 1000 atm | 1,013.25 bar |
Exact factor: 1 atmosphere = 1.01325 bar. Values rounded for display.